Method and apparatus for forming high strength products

ABSTRACT

A system and method are presented in which a flow of plastic is extruded to obtain nano-sized features by forming multiple laminated flow streams, flowing in parallel through the non-rotating extrusion system. Each of the parallel laminated flow streams are subjected to repeated steps in which the flows are compressed, divided, and overlapped to amplify the number of laminations. The parallel amplified laminated flows are rejoined to form a combined laminated output with nano-sized features. The die exit is formed to provide a tubular shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S.Provisional Patent Application Ser. No. 61/460,042, filed on Dec. 23,2010, the disclosure of which is incorporated herein by reference in itsentirety.

BACKGROUND

1. Field

The aspects of the present disclosure generally relate to extrusion diesystems. In particular, the aspects of the present disclosure relate tothe cyclical extrusion of materials to generate small sized grainfeatures, generally in the range of micro and nanosized grain featuresto improve the strength of extruded products

2. Brief Description of Related Developments

Nanostructured materials are generally regarded as materials having verysmall grain feature size, typically in the range of approximately 1-100nanometers (10⁻⁹ meters). Metals, ceramics, polymeric and compositematerials may be processed in a variety of ways to form nanosizedfeatures. These materials have the potential for wide rangingapplications, including for example, industrial, biomedical andelectronic applications. As a result, a great deal of study is ongoingto gain a better understanding of the characteristics of thesematerials.

Conventional extrusion formed products are limited to approximatelytwelve layers. Micro-layer extrusion processes can extend theselimitations. A micro-layer extrusion process that provides a method forobtaining small grain features is described in U.S. Pat. No. 7,690,908,(the “'908 Patent”) commonly owned by the assignee of the instantapplication, the disclosure of which is incorporated herein by referencein its entirety. The disclosure of the '908 Patent describes a system ofdies that are constructed to adapt extrusion technology. Examples ofsuch extrusion technology are described in U.S. Pat. Nos. 6,669,458,6,533,565 and 6,945,764, commonly owned by the assignee of the instantapplication.

The typical micro-layer product is formed in a sheet. If a tubularproduct is desired, the microlayer is first formed into a sheet and thenmade into the tube. This creates a weld line or separation between themicrolayers. The '908 Patent describes a cyclical extrusion of materialsby dividing, overlapping and laminating layers of flowing material,multiplying the flow and further dividing, overlapping and laminatingthe material flow to generate small grain features and improveproperties of the formed product. Examples of the improved propertiesinclude, but are not limited to burst strength, tensile strength, tearresistance, barrier and optical properties. Referring to FIGS. 1 and 2,a series of die plates 100 are configured to receive a flow of material,such as plastic or other suitable material, at 101. The firstdistribution module 110 divides the flow into multiple capillary streamsand distributes the flow downstream to a transition module 111. Thetransition module 111 further divides the streams and transforms theshape of the generally circular capillary streams into thin ribbon likestreams. At the exit of the transition module 111 the flow crosssectional area of each ribbon stream may be reduced by a compression ofthe flowing material. At the output of the transition module 111, setsof adjacent ribbons (a pair as shown) are directed to a firstcompression stage in die plate 6 of compression/layering module 112.Each set of ribbon pairs is processed into a layered flow. This layeredflow comprises a laminate of the sets of adjacent ribbons. The firststage compression die plate 6 also splits the laminated ribbons into atleast a pair of adjacent ribbons. At this stage, the original plasticflow is considerably altered and now comprises at least side by side,multiple parallel flows in the form of laminated ribbons.

As shown in FIGS. 1 and 2, each of these flows are subjected to a seriesof cycles in which the ribbons are compressed, divided and overlapped tomultiply the number of laminations. In one embodiment, this cycle isrepeated in a chain of extrusion stages of this construction, resultingin increasing numbers of thinner laminations formed within the extrusionflow. In the case of dual side by side flows, the number of laminationswould be doubled at each stage.

By first distributing the flowing plastic into a set of multiple streamsand then combining the multiple streams into a series of laminatedstreams, a group of parallel streams, oriented above and below, as shownin FIG. 1, may be processed in parallel and rejoined to generatecombined flow stream. At the die system exit, generally shown at 106, alaminated plastic flow is achieved having a significantly high number ofthin laminations in which micro and nano-sized features may be formed.By controlling the number of compression, division, and laminationcycles, the thickness of the laminations may be adjusted. As describedin the '908 Patent, it is advantageous that a basic die system includedividing the stream into at least a pair of flow streams to take fulladvantage of multiple cycles of compression, dividing and layering. Inthe '908 Patent, multiple pairs of flow streams are stacked in aparallel relationship.

The '908 Patent relies on the cyclical extrusion of materials. Theoutput plastic flow, also referred to as the rejoined flow, is appliedto final die elements 120 that wind the laminated plastic flow into atubular end product having nano-sized features. U.S. Pat. No. 6,669,458,(“the '458 Patent”), commonly owned by the assignee of the instantapplication and the disclosure of which is incorporated herein byreference in its entirety, discloses one embodiment of an extrusion diewith rotating components. Referring to FIG. 3, a cross-sectional view ofan extrusion die having balanced flow passages and rotating elements isillustrated.

The extrusion system 150, shown in FIG. 3 is configured to extrude atubular product constructed of common thermoplastic materials. Thesystem 150 includes an extruder 152 designed to provide a moltenmaterial, such as plastic, to an extrusion die 153. The extrusion die153 consists of a series of components including a die body 154, and adie module 156. When assembled, the extrusion die 153 of thesecomponents is constructed having a passage 157 therein extending from anupstream inlet 158 to a downstream outlet 159. The passage 157 is formedby the cooperation of adjacent components and the individual componentsof the passage communicate to provide a continuous passage 157 for theflow of molten plastic through the extrusion die 153. This passage isconstructed to provide a balanced flow of plastic to and throughout anextrusion channel 23 which is formed downstream as described below.

Flow channel(s) 161 are connected to inlet 158 and a divider 162separates the incoming stream of plastic evenly into the two channels.Flow channels 161 are constructed in the die body 154 and extend throughthe die body 154 to respective outlets (not shown), in the transverselyoriented downstream face 165 of the die body 154. A distribution groove166 is formed in the downstream face 165 between an upstream edge and adownstream edge. The distribution groove 166 communicates with theoutlets to receive molten plastic from the flow channels 151. Thedistribution groove 166 is substantially semicircular in cross sectionand extends in an annular manner concentric with the axis 24 of theextrusion die 3. The flow of plastic will be around the distributiongroove 166 from each of the outlets. The flow will be in two opposingpaths within the groove 166.

The die body 154 and die module 156 are constructed with axiallyextending bores 25 and 26 respectively which align to form a continuousopening along the axis 24 of the extrusion die 153. A tip module 155 isconstructed to fit within the bore 25/26. A clearance is formed betweenthe inner surface of the bore 26, and the outer surface of the tip 155to form the extrusion channel portion 23 and the exit portion 27 of theplastic passage 157. A conical surface 22 is constructed on the outersurface of the tip module 155 and cooperates with a conical portion ofthe bore 26 to form the tapered extrusion channel 23. The tip 155 may beconstructed with an axial bore 30 to allow an elongated element to passthrough the die for coating. The '458 Patent provides for relativerotational movement between the surfaces 28 and 29.

A rotary die assembly requires specialized parts and configurations toaccommodate the rotating surfaces as well as the high temperaturesinvolved in these processes. It would be advantageous to be able createa tubular product using an extrusion system with or without the need forrotating components.

All tubular products made by an extrusion die possess a knit or weldline due to the supports required for the tip or mandrel in the diescenter. A rotary die twists the polymer, so the knit lines get mixedinto a seamless product, potentially eliminating the weld line andmaking the tube stronger. The tube also spins when it exits the die,which can create a helical appearance i.e. addition of stripes. Thespinning tube can also be utilized to aid in a coating process.

Accordingly, it would be desirable to provide a system that addresses atleast some of the problems identified above.

BRIEF DESCRIPTION OF THE ASPECTS OF THE PRESENT DISCLOSURE

As described herein, the exemplary embodiments overcome one or more ofthe above or other disadvantages known in the art.

One aspect of the exemplary embodiments relates to a method. In oneembodiment, the method includes extruding a flow of extrusion materialin a non-rotating extrusion assembly, forming a first set of multiplelaminated flow streams from the extruded flow, amplifying a number ofthe laminations by repeatedly compressing, dividing and overlapping themultiple laminated flow streams, rejoining the parallel amplifiedlaminated flows, forming a first combined laminate output withnano-sized features from the rejoining; and forming a tubular shapedmicro-layer product from the combined laminate output.

Another aspect of the exemplary embodiments relates to an apparatus. Inone embodiment, the apparatus includes a non-rotating micro-layerextrusion assembly. In one embodiment, the assembly includes anextrusion material distribution system, at least one multiple laminateflow passage configured to amplify a number of laminations of each flowstream by repeatedly compressing, dividing and overlapping each of themultiple laminate flow streams, and an exit die having an exit flowpassage coupled to the multiple laminate flow passage, the exit dieconfigured to generate an inner and an outer annular segment for themultiple laminate flow stream and wherein the exit flow passage isskewed from a parallel direction of the flow stream at a pre-determinedhelical pitch angle relative to a central axis of the non-rotatingextrusion assembly.

A further aspect of the disclosed embodiments relates to a micro-layertubular extrusion product. In one embodiment the product comprises atleast one micro-layer having nano-sized features. The at least onemicro-layer is formed by receiving a flow of extrudible material innon-rotating micro-layer extrusion assembly, constructing a series ofribbon shaped flow streams, subjecting the ribbon shaped flow streams tomultiple sequences of stages, wherein, in each of the sequences the flowstreams are compressed. In one embodiment, the sequences further includejoining sets of the series of ribbon shaped flow streams to formmultiple laminated flow streams flowing in parallel, dividing each ofthe multiple parallel laminated flow streams into at least two adjacentflow streams while compressing the resulting flow streams to formthinner laminations, overlapping the adjacent flow streams to form aflow stream, thereby multiplying the number of laminations, repeatingthe dividing and overlapping steps in parallel for each of the multipleparallel laminated flow streams to multiply the number of laminationsand to generate progressively thinner laminations until nano-sizedfeatures are obtained, providing an output flow stream from the multiplesequences of stages, the output flow stream comprising an inner andouter annular segment, and bonding adjacent ends of the inner and outerannular segments together to form the tubular micro-layer product.

These and other aspects and advantages of the exemplary embodiments willbecome apparent from the following detailed description considered inconjunction with the accompanying drawings. It is to be understood,however, that the drawings are designed solely for purposes ofillustration and not as a definition of the limits of the invention, forwhich reference should be made to the appended claims. Moreover, thedrawings are not necessarily drawn to scale and unless otherwiseindicated, they are merely intended to conceptually illustrate thestructures and procedures described herein. In addition, any suitablesize, shape or type of elements or materials could be used.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a transparent perspective view of one embodiment of anextrusion system for obtaining nano-sized features;

FIG. 2 is a top view of the extrusion system shown in FIG. 1;

FIG. 3 is a cross-sectional view of one embodiment of an extrusion dieassembly having balanced flow passages and rotating elements;

FIG. 4 is a perspective view of an extrusion die system incorporatingaspects of the disclosed embodiments;

FIG. 5 is a perspective view of one embodiment of an input distributionmodule of the system shown in FIG. 4;

FIG. 6 is perspective view of one embodiment of the input distributionmodule and a transition module for the system shown in FIG. 4;

FIG. 7 is a sectional view of the embodiment of FIG. 4 taken alongsection lines A-A;

FIG. 8 is a sectional view of the embodiment of FIG. 4 taken alongsection lines B-B;

FIG. 9 is a sectional view of the embodiment of FIG. 4 taken alongsection lines C-C;

FIG. 10 is a sectional view taken along the center axis of theembodiment shown in FIG. 4.

FIG. 11 is a perspective view of the preform at the die exit in theembodiment of FIG. 4;

FIG. 12 is an enlarged view of a portion of the preform of FIG. 13;

FIG. 13 illustrates a tongue and groove bonding seam for the preform ofFIG. 11;

FIG. 14 illustrates an alternate embodiment of the present disclosureillustrating a system of die plates arranged to apply a laminatedcoating over a tubular substrate;

FIG. 15 is perspective view of an second alternative embodiment of thepresent disclosure illustrating a die system arranged to apply alaminated coating over a tubular substrate and an outer coating to thelaminated coating;

FIG. 16 is a perspective view of the embodiment of FIG. 15, partiallycut away upstream of the die output, illustrating the relationship amongthe passages for the tubular substrate, the laminated coating and theouter coating;

FIG. 17 is a perspective view of the embodiment of FIGS. 15 and 16,partially cut away further upstream of the die output, to show thedistribution module for the outer coating;

FIG. 18 is a perspective view of the embodiment of FIGS. 15, 16 and 17,partially cut away still further upstream of the die output, to show thedistribution module for the tubular substrate;

FIGS. 19-25 are perspective views of alternate embodiments of thepresent disclosure illustrating different numbers and configurations offlow passages and output streams;

FIG. 26 is an alternate embodiment of the present disclosureillustrating the use of the extrusion die system and assembly of FIG. 4incorporated into a rotating die assembly

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

Referring to FIG. 4, an extrusion die system incorporating aspects ofthe present disclosure is generally designated by reference numeral 200.The aspects of the present disclosure are generally directed to anextrusion system for producing nano-sized features by forming multiplelaminated flow streams. Although the aspects of the present disclosurewill be described with reference to the embodiments shown in thedrawings, it should be understood that the aspects of the presentdisclosure may have many alternative forms.

The aspects of the present disclosure are configured to extrude a streamof material, such as resin or plastics, into articles having anassortment of different shapes. The articles can include for example,but are not limited to, tubular or cylindrical shapes. The finishedproduct or article will have small grain features, and in particular ofa micro or nanometer size. This is accomplished for a tubular productwith or without relying on the use of rotating die components.

Referring to FIG. 4, in one embodiment, the extrusion system 200generally comprises an array 199 of die plates 202 that are configuredto receive and process a flow of extrusion material, such as resin orplastic, received through or from one or more sources 201, 204 in adirection indicated by arrow 203. Although the system 200 shown in FIG.4 illustrates two sources 201, 204, in alternate embodiments more orless than two sources can be used. Additional, each source 201, 204 cancomprise a different material. Each of the die plates 202 is generallyconfigured to generate a cumulated laminated output with nano-sizedfeatures, similar to the output generated by the system disclosed in the'908 Patent. For purposes of the description herein, only the die plates202 are shown. The sequence of die plates includes a first stage of dieplates constructed to receive the flow of extrudible material and dividethe flow into multiple ribbon shaped flow streams, a second stage of dieplates constructed to receive the multiple ribbon shaped flow streamsand further divide each of the multiple ribbon shaped flow streams intoat least two ribbon shaped flow streams. The second stage of die platesis also configured to layer the two ribbon shaped flow streams intocomposite laminated flow streams. A third stage of die plates isconfigured to receive the composite laminated flow streams and to againdivide each of the composite laminated flow streams into at least tworibbon shaped flow streams. The third stage of die plates is configuredto layer the two ribbon shaped flow streams into composite laminatedflow streams, wherein the number of laminations is multiplied andcompressed.

In the embodiment illustrated in FIG. 4, the extrusion system 200 isconfigured to divide the flow of plastic material 201 a, 204 a into four(4) flow passages, also referred to as flow streams, generally indicatedas 205-208. Although for the purposes of the description herein on fourflow streams are illustrated, in alternate embodiments any suitablenumber of flow streams can be utilized, including more or less thanfour. For example, as will be described further herein, otherembodiments are illustrated showing configurations using one, two,three, six and eight flow streams flowing in a direction generallyparallel to a central axis X-X of the extrusion die system 200.

The multiple streams 205-208 of plastic flow 201 a, 204 a generate pairsof flow streams that are subjected to repeated cycles of compression,division, and lamination, similar to the process described in the '908Patent. In an embodiment of the present disclosure, unlike the processdescribed in the '908 Patent, the multiple streams 205-208 are notstacked immediately adjacent, as in the parallel flow streams of the'908 Patent, but are rather uniquely and advantageously arranged in anarray 199 with each stream flowing along an axis that is parallel, butdisplaced, in a plane transverse to the primary direction of flow 203.

As is shown in FIG. 4, in one embodiment, the pattern of the array 199may be substantially rectangular with an axis of each flow stream205-208 being displaced approximately 90 degrees in a plane transverseto the axis of an adjacent flow stream 205-208. In alternate embodiment,the array 199 can comprise any suitable geometric shape, includingsubstantially circular, oval or square. In the embodiment of FIG. 4, thefour flow streams 205-208 are arranged at approximately 90 degreeintervals around the central axis X-X of the die system 200. In oneembodiment, opposing pairs of flow streams, such as 205 and 207 or 206and 208, are substantially parallel to each other. Each of the four flowstreams 205-208 will be compressed, divided, and layered and thencombined to form a tubular product output having multiple thinlaminations at the die system exit 250.

In addition, the aspects of the present disclosure may be configured toprovide an axially aligned tubular substrate onto which the laminatedoutput of the die system 200 may be extruded. In a further embodiment anouter coating layer may be applied to the laminated tubular output ofthe die system 200. Further embodiments are described in which multiplematerials may be supplied to provide the laminating flow streams toenhance the strength of the laminated tubular product.

In the embodiment of FIG. 4, the extrusion die system 200 generallyincludes a distribution module 220, a transition module 230, alaminating module 240, and a die exit 250. In one embodiment, each setof die plates 202 includes a transition and laminating module. Inalternate embodiments, the transmission module and laminating module isintegrated with separate flow passages for each stream 205-208. Thetransition module 230 and laminating module 240 generally correspond tothe transition stage 111 and laminating stage 112 of the '908 Patent,the disclosure of which is incorporated herein by reference.

In one embodiment, the distribution module 220 includes one or moreplates, such as plates 110 a and 110 b shown in FIG. 2, which areconfigured to receive the flow(s) of material 201, 204 from a source(not shown) and divide the flow 201 a, 204 a of material into multiplecapillary streams 205-208. The capillary streams 205-208 are passedthrough transmission module 230.

The transmission module 230 is generally configured to form each of thestreams 205-208 into a ribbon like stream that is directed to thelaminating module 240. The transmission module 230 is constructed havingmultiple die plates, such as plates 111 a-c shown in FIG. 2, arranged insequence to process each of the capillary streams 205-208, namely, tocompress, divide, and laminate each of the flow streams 205-208, asdescribed in more detail in the '908 Patent.

As noted above, the composite flow stream 201 a, 204 a may be comprisedof a single material from one source. Alternately, the composite flowstream 201 a, 204 a comprises two or more different materials frommultiple sources. As shown in the embodiment of FIG. 4, two differentmaterials, 201 and 204 are supplied to the die system 200 anddistributed to each of the flow streams 205-208. For purposes of thedescription herein, each of the laminated flow streams 205-208 shown inthis example can be comprised of a composite of the two materials 201,204.

It should be noted that it is a purpose of this arrangement of dieplates 202 is to convert each input flow 201 a, 204 a, into a group ofparallel laminated flows 205-208, as illustrated in FIGS. 4 and 8. Thenumber of flow streams and groups formed may depend on a variety offactors and the aspects of the present disclosure are not intended to belimited to the number of flow streams and groups shown. Multipleparallel flows are advantageous to reduce the overall length and footprint of the extrusion system 200 when nano-sized grain features areneeded.

Referring to FIG. 5, the distribution module 220 is configured toreceive incoming stream(s) 201 a, 204 a of materials 201, 204 and dividethe input streams 201 a, 204 a into eight (8) capillary flow streams,generally referenced by 211-218. A pair of two flow streams will formone of the flow streams 205-208. For example, pair 211, 212 forms flowstream 205 in the example shown in FIGS. 4 and 5.

Referring to FIG. 6, the transition module 230 is configured to receivethe eight capillary streams 211-218 and process them through transitiondie passages 231-238 to form a group of eight ribbon shaped streams. Theeight output ribbons or streams are compressed, combined and supplied tothe lamination module 240 for processing in the four laminating flowstreams 241-244, as shown in FIGS. 4, 8 and 9. As shown in FIG. 6, eachof transition die passages 231-238 is generally shaped to transform thesubstantially tubular shaped streams from distribution module 220 intosubstantially rectangular ribbon shapes for further processing. Theinput flow from the transition module 230 to the lamination module 240is best shown in FIG. 7.

According to the embodiment shown in FIGS. 4-9, the flow streams205-209, and corresponding modules 220-250, are configured in asubstantially dispersed array 199 having a direction of flow parallel tothe central axis X-X of the extrusion die system 200. This configurationis particularly advantageous for the extrusion of tubular shapedproducts. It also provides a central space 251 for the forming of asubstrate (not shown) onto which the tubular output of the laminatedflow streams 205-208 may be extruded.

FIG. 7 illustrates a cut away view along a generally horizontal axialcross section of the laminating module 240, illustrating in particular,the lower flow stream 244. A further cut away view along a verticalcross section is shown in FIG. 8, thereby fully illustrating the overallcomponents of the die system 200 of the embodiment shown and describedwith reference to FIG. 4. In order to illustrate schematically thedivision step of each of the laminating steps of laminating module 240,a sectional view, taken in a plane transverse to the axis X-X of FIG. 4is presented in FIG. 9. In this view the division passages 241 a, 241 b,2421, 242 b, 243 a, 243 b and 244 a, 244 b of the flow passages 241-243are illustrated. FIG. 10 is a cross-sectional side view of theembodiment shown in FIG. 4.

As shown in FIGS. 4-10, the flow of material in each of the flowpassages or streams 205-208 and 241-244, subjects the material torepeated steps of compression, division, and layering until reaching thedie exit 250. The flow streams of each group are in the form oflaminated ribbons and retain a layered structure corresponding to thenumber of laminations. This structure is maintained throughout theextrusion process, except for increased numbers of thinner and thinnerlaminations, the numbers of which are only limited by the particulardesign and product requirements.

As shown in FIGS. 4-9, the laminating module 240 includes one or morelaminating phases or steps in each of the laminating flows 241-244, suchas phase 245 in flow 242. At each laminating phase or step within thelaminating module 240, the material is compressed, divided andoverlapped to multiply the number of laminations. By subjecting the flowof material to a chain of extrusion stages of this construction,exponentially increasing numbers of gradually thinner laminations may beformed within the extrusion flow, thereby obtaining smaller and smallergrain features and eventually obtaining nano-sized features. A computergenerated depiction of a preform 300 formed by this process is shown atthe die exit 250 in FIGS. 11 and 12.

With reference to FIGS. 7-11, the four parallel laminated flows 241-244are each split into pairs of inner and outer exit flows, also referredto as exit flow passages or streams. FIGS. 7-8 illustrate aspects of theexit flow pairs 252, 253 for flow passage 241, pairs 254, 255 for flowpassage 242, and pairs 256, 257 for flow passage 243 and 258, 259 forflow passage 244.

In one embodiment, referring to FIGS. 4 and 10, each passage 252-259 ofthe die exit 250 is skewed from the generally parallel directionmaintained in flow streams 241-244 at a predetermined helical pitchangle to the axis X-X. In this manner a tubular shape may be formed fromthe output. FIG. 10 illustrates one embodiment of the angledconfiguration of the exit flow passages or streams 254, 255, 258 and259.

FIG. 11 illustrates an embodiment with five flow streams 351-355. Theexit passages 311-315 and 321-325 form a total of ten (10) annularsegments that are the result of the ten laminated streams. In thisexample, the output of each of the inner and outer pairs of exit flowpassages/streams 311-315 and 321-325 are combined to form a singleoutput preform 300 at die exit 250, as illustrated, in exaggerated size.Because of the joining of the ten resulting laminated streams from thepassages 311-315 and 321-325, the output perform 300 will have distinctboundary features 302 as shown in FIGS. 11 and 12. Although theseboundary features 302 will be microscopic in nature, they may causeweakness in the overall tubular product. To avoid this and to provide anintegrated tubular perform shape, in one embodiment, the die exit 350 isconstructed to reshape the ribbon shaped streams received from thelaminating module 240 into annular segments including outer annularsegments 311-315 and inner annular segments 321-325, as shown in FIG.11.

In one embodiment, as is shown in FIGS. 11 and 12, the inner 311-315 andouter 321-325 annular segments may be offset so that the boundaryfeatures 302, also referred to herein as “seams”, formed during joiningof the flow streams are not aligned, or are staggered. The overlappingand staggering of the seams 302 makes for a much stronger end productbecause the contact area is increased. The “weld” is substantially arcshaped, where the load has much more surface area and the load is inshear. In alternate embodiments, the boundary features 302 can bealigned. In one embodiment, the boundary features or seams 302 can bealigned and butt-welded together. This configuration can be advantageouswhen it is desirable to embed a material or substance between the seams302. FIG. 11 illustrates a staggered arrangement of seams 302 that arejoined together using a suitable bonding mechanism.

In one embodiment, referring to FIG. 13, a bonding mechanism, such asfor example a tongue and groove bonding mechanism or pattern 320, can beapplied to each of the boundary features 302 between adjacent segments,such as 311, 312. This can help in improving the continuity of the seamas well as the strength.

The aspects of the disclosed embodiments form a tubular product thatcombines integrated laminated streams having small size grain featuresand helical grain orientation. The tubular product that is produced bythe die extrusion system 200 of the disclosed embodiments exhibitssuperior strength characteristics and flexibility. While a tubularstructure is generally referred to herein, the processes and apparatusof the disclosed embodiments provide significant latitude to design awide variety of structures not limited to tubular shapes andconfigurations, but adaptable to many different shapes.

Referring to FIG. 14, the arrangement of flow paths as shown in FIG. 4and other embodiments provides space along the axis of the die system200 for the installation of a central die passage 400 aligned with theaxis X-X in conjunction with an extrusion die system 200 incorporatingaspects of the disclosed embodiments. FIG. 14 shows an embodiment havingan axial die passage 400 through which a tubular substrate 402 of amaterial 406 may be passed. The passage 400 may be supplied by anindependent source of material 406 (which in one embodiment can compriseone or more of the sources 201, 204 shown in FIG. 4) and conveyed to thepassage 400 in a balanced flow groove 408 constructed in die plate 402.This allows the application of the output laminated flow 410, created inaccordance with the aspects of the extrusion die system 200 disclosedherein, to a tubular substrate at the die exit 250.

A second alternate embodiment is described with reference to FIGS. 15and 16. In this embodiment, the die exit 250 is surrounded by a dieelement 500 having a conical die passage 502 for extruding an outercoating of a material 512 over the laminated output. Although the outerdie passage 502 may be constructed in the absence of a tubular substratepassage 504, both passages 502 and 504 are shown in FIG. 16. FIG. 16illustrates the relative position of substrate passage 504, laminatedflow streams 241-244 and outer die passage 502 in a cut away view takenupstream of the die exit 250. A further illustration showing thedistribution module 520, similar to distribution module 220 of FIG. 4,that feeds the outer die passage 502 is contained in FIG. 17. As shownin FIG. 17, the distribution module 520 is comprised of input passages524 connected to a balanced groove 526. In this embodiment, it ispossible to construct a tubular product having a tubular substrate of afirst material, a laminated tubular component constructed of a compositeof second and third materials and an outer coating of a fourth material.This advantageously provides a significant range of design latitude.

Several aspects and further embodiments of the die system 200 of thisapplication are illustrated in FIGS. 19-23 in which embodiments areshown constructed having different arrays of flow passages or streams,different boundary alignments, resulting in different flow outputs.

FIG. 19 illustrates a configuration processing and outputting a singleflow stream 601 from the set of dies 202. The output 602 from the dieexit 250 includes a boundary or seam 603. In this example, the boundaryor seam 603 results from joining each end 604, 605 of the flow output602 together.

FIG. 20 illustrates the result of the processing of two flow streams ormicro-layer channels 610, 611 that are configured or offsetapproximately 180 degrees apart. In this example, the processing of eachflow stream 610, 611 by the system 200 described herein results in outerannular segments 612, 613 and inner annular segments 614, 615. The seams616-619 are staggered and bonded together.

FIG. 21 illustrates three micro-layer channels 621-623 oriented atapproximately 120 degrees apart or offset relative to the central axis.This configuration results in outer annular segments 624 a-c and innerannular segments 625 a-c, and staggered seams 627 a-c and 628 a-c.

FIG. 22 illustrates annular segments 631 a-f and 632 a-f resulting froman arrangement of six flow streams in six micro-layer channelsconfigured at an offset of approximately 60 degrees relative to oraround an axis of the central channel X-X. In this example, therespective seams 633 and 634 are staggered.

FIG. 23 illustrates annular segments 643 a, b and 644 a, b resultingfrom the processing of two flow streams in two micro-layer channels 641,642 that configured or offset at approximately 180 degrees relative toone another around the central axis X-X. In this example, the boundariesor seams 645 a, 645 by 645 are not offset, but rather aligned with eachof the respective inner and outer exit flow pairs. In this example, theseams 645 a and 645 b are butt-welded together.

In FIG. 24, three micro-layer channels offset at approximately 120degrees relative to one another around the central X-X produce inner andouter annular segments generally referred to as 651-653, with alignedand butt-welded seams 654-656.

In FIG. 25, four micro-layer channels offset at approximately 90 degreesrelative to one another around the central X-X produce inner and outerannular segments generally referred to as 661-664, with butt-weldedseams 665-669.

These embodiments are presented as examples of the many configurationspossible utilizing the basic elements described herein and furtherdemonstrate the significant design flexibility provided by the aspectsof the present disclosure described herein.

FIG. 26 illustrates one embodiment of the present disclosure where theextrusion die system 200 shown in FIG. 4 is incorporated with rotatingcomponents to create a rotary die assembly 700. As shown in FIG. 26, thefeedblock for the rotary extrusion die system 700 is internal to thesystem 700. There is no external feedblock. By the time the productcreated by the individual die exit 250 of the extrusion system 200 isintroduced into the rotating components of the rotating extrusion dieassembly 700, the product is already in the form of a tube, which isadvantageous. In one embodiment, the rotating aspect of the system 700takes the tubular product formed by the extrusion system 200 and twistsit, potentially eliminating any weld lines or seams 302 entirely, whichis advantageous, since the weld line 302 or separation between themicrolayers can be a point of weakness.

Aspects of the rotating components for the rotary die assembly 700 canbe taken from the rotary die assembly 150 shown in FIG. 3. One exampleof such a rotary die assembly is the rotary die assembly described incommonly owned U.S. Pat. Nos. 6,447,279 and 6,669,458, the disclosuresof which are incorporated herein by reference in their entirety.

As is shown in FIG. 26, the extrusion system 700 is constructed toextrude a tubular product constructed of common thermoplastic materials.The system 700 includes a series of components including a die body 704,and a die module 706. The die body 704 and die module 706 areconstructed with axially extending bores that align to form a continuousopening 725 along the axis 724 of the assembly 700. A tip module 705 isconstructed to fit within the opening 725. A clearance is formed betweenthe inner surface of the bore 725 and the outer surface of the tip 705to form the extrusion channel portion 723 and the exit portion 727. Aconical surface 722 is constructed on the outer surface of the tipmodule 705 and cooperates with a conical portion of the bore 725 to formthe tapered extrusion channel 723. The tip 705 may be constructed withan axial bore 730 to allow an elongated element to pass through the diefor coating. Aspects of the '458 Patent can be utilized to providerelative rotational movement between the surfaces 728 and 729.

In one embodiment, the extrusion die assembly 200 of the presentdisclosure can be incorporated within an extrusion blow molding system.In this embodiment, the extrusion die assembly 200 is used to providethe cumulated laminated output with nano-sized features in a tubularform to the shaping aspect of an extrusion blow molding system. In thisaspect, a more durable tubular blow molding product can be created,which incorporates many of advantages described herein.

The aspects of the disclosed embodiments create small grain products,such as tubular products, without relying on the use of rotating diecomponents. In a rotary die configuration, the aspects of the disclosedembodiments create an array of feedblocks in the extrusion die itself.There is no external feed-block component. By the time the product thatis created by the extrusion die system of the disclosed embodimentsreaches the rotating components, the product is already in the form of atube.

Thus, while there have been shown, described and pointed out,fundamental novel features of the invention as applied to the exemplaryembodiments thereof, it will be understood that various omissions andsubstitutions and changes in the form and details of devicesillustrated, and in their operation, may be made by those skilled in theart without departing from the spirit of the invention. Moreover, it isexpressly intended that all combinations of those elements and/or methodsteps, which perform substantially the same function in substantiallythe same way to achieve the same results, are within the scope of theinvention. Moreover, it should be recognized that structures and/orelements and/or method steps shown and/or described in connection withany disclosed form or embodiment of the invention may be incorporated inany other disclosed or described or suggested form or embodiment as ageneral matter of design choice. It is the intention, therefore, to belimited only as indicated by the scope of the claims appended hereto.

What is claimed is:
 1. A method of extruding a tubular flow of extrusionmaterial in from a non-rotating extrusion assembly comprising forming afirst set of multiple laminated flow streams flowing parallel to acentral axis; amplifying the number of the laminations by repeatedlycompressing, dividing and overlapping the multiple laminated flowstreams to form a second set of multiple laminated flow streams withmicro to nano-sized features flowing parallel to said central axis;combining said laminate flow streams as annual segments; and extruding atubular shaped product from the combined laminate output in an exit flowpassage of the nonrotating extrusion assembly.
 2. The method of claim 1,wherein forming the tubular shaped product comprises: introducing thecombined laminate output into an exit flow passage of the non-rotatingextrusion assembly, the exit flow passage being skewed from a paralleldirection of the flow stream at a pre-determined helical pitch anglerelative to a central axis of the non-rotating extrusion assembly; andbonding the annular segment ends of the combined laminate output.
 3. Themethod of claim 1, comprising forming at least one other set of multiplelaminated flow streams in the extruded flow, each other set of multiplelaminated flow streams being offset from the first set of multiplelaminated flow streams by an angle around the central axis; amplifying anumber of the laminations of each other set by repeatedly compressing,dividing and overlapping the second set of multiple laminated flowstreams; rejoining the parallel amplified laminated flows; forming atleast one other combined laminate output with micro to nano-sizedfeatures from the rejoining; and joining each of the other combinedlaminate output with the first combined laminate output to form thetubular shaped product.
 4. The method of claim 3, wherein joining eachother combined laminate output with the first combined laminate outputto form the tubular shape comprises: introducing the first and eachother combined laminate output into respective exit flow passages toform inner and outer annular segments for each combined laminate output,the respective exit flow passages being skewed from a parallel directionof the flow stream at a pre-determined helical pitch angle relative to acentral axis of the non-rotating extrusion assembly; and bonding eachend of adjacent inner and outer annular segments together.
 5. The methodof claim 4, wherein a seam formed by the bonding of each end of an innerannular segment is substantially aligned with a seam formed by thebonding of each end of a corresponding outer annular segment.
 6. Themethod of claim 4, wherein a seam formed by the bonding of each end ofan inner annular segment is substantially staggered with respect to aseam formed by the bonding of each end of a corresponding outer annularsegment.